David DiSalvo is the author of "Brain Changer: How Harnessing Your Brain’s Power to Adapt Can Change Your Life" and the best-selling "What Makes Your Brain Happy and Why You Should Do the Opposite", which has been published in 10 languages. His work has appeared in Scientific American Mind, Forbes, Time, Psychology Today, The Wall Street Journal, Slate, Salon, Esquire, Mental Floss and other publications, and he’s the writer behind the widely read science and technology blogs “Neuropsyched” at Forbes and “Neuronarrative” at Psychology Today. He can be found on Twitter @neuronarrative and at his website, daviddisalvo.org. Contact him at: disalvowrites [at] gmail.com.

What Eating Too Much Sugar Does to Your Brain

Overeating, poor memory formation, learning disorders, depression – all have been linked in recent research to the over-consumption of sugar. And these linkages point to a problem that is only beginning to be better understood: what our chronic intake of added sugar is doing to our brains.

According to the U.S. Department of Agriculture (USDA), the average American consumes 156 pounds of added sugar per year. That’s five grocery store shelves loaded with 30 or so one pound bags of sugar each. If you find that hard to believe, that’s probably because sugar is so ubiquitous in our diets that most of us have no idea how much we’re consuming. The Centers for Disease Control (CDC) puts the amount at 27.5 teaspoons of sugar a day per capita, which translates to 440 calories – nearly one quarter of a typical 2000 calorie a day diet.

The key word in all of the stats is “added.” While a healthy diet would contain a significant amount of naturally occurring sugar (in fruits and grains, for example), the problem is that we’re chronically consuming much more added sugar in processed foods. That’s an important clarification because our brains need sugar every day to function. Brain cells require two times the energy needed by all the other cells in the body; roughly 10% of our total daily energy requirements. This energy is derived from glucose (blood sugar), the gasoline of our brains. Sugar is not the brain’s enemy — added sugar is.

Research indicates that a diet high in added sugar reduces the production of a brain chemical known as brain-derived neurotrophic factor (BDNF). Without BDNF, our brains can’t form new memories and we can’t learn (or remember) much of anything. Levels of BDNF are particularly low in people with an impaired glucose metabolism–diabetics and pre-diabetics–and as the amount of BDNF decreases, sugar metabolism worsens.

In other words, chronically eating added sugar reduces BDNF, and then the lowered levels of the brain chemical begin contributing to insulin resistance, which leads to type 2 diabetes and metabolic syndrome, which eventually leads to a host of other health problems. Once that happens, your brain and body are in a destructive cycle that’s difficult if not impossible to reverse.

Research has also linked low BDNF levels to depression and dementia. It’s possible that low BDNF may turn out to be the smoking gun in these and other diseases, like Alzheimer’s, that tend to appear in clusters in epidemiological studies. More research is being conducted on this subject, but what seems clear in any case is that a reduced level of BDNF is bad news for our brains, and chronic sugar consumption is one of the worst inhibitory culprits.

Other studies have focused on sugar’s role in over-eating. We intuitively know that sugar and obesity are linked, but the exact reason why hasn’t been well understood until recently. Research has shown that chronic consumption of added sugar dulls the brain’s mechanism for telling you to stop eating. It does so by reducing activity in the brain’s anorexigenic oxytocin system, which is responsible for throwing up the red “full” flag that prevents you from gorging. When oxytocin cells in the brain are blunted by over-consumption of sugar, the flag doesn’t work correctly and you start asking for seconds and thirds, and seeking out snacks at midnight.

What these and other studies strongly suggest is that most of us are seriously damaging ourselves with processed foods high in added sugar, and the damage begins with our brains. Seen in this light, chronic added-sugar consumption is no less a problem than smoking or alcoholism. And the hard truth is that we may have only begun to see the effects of what the endless sugar avalanche is doing to us.

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With obesity doubling over the past 30 years, it is almost a given that Congress will pursue a tax on unhealthy consumption. The question is whether it is more politically feasible to pass a fat tax or a sugar tax; certainly it would be a stretch to pass both. U.S. agribusiness is more heavily invested in beef and beef by-products than in sugar (the latter of which is heavily imported), and so there would likely be greater political opposition by beef processing and distribution firms than by sugar processors and distributors. Either way, bakery would definitely cost more, but at least a sugar tax would not raise the cost of the “meat and potatoes” portion of a meal.

As if a sugar tax would be feasible. The last thing anyone with any amount of common sense is to have more Government in our lives, food included. What we have is big corn, big beef, agencies telling us what to consume and what not to like the FDA. Let people eat what they want as there bodies are there property and they are within there right to do what they want just as long as it does not harm others. If they need help, the help should be managed within a private health market. Why should my taxes be taken to assist people who are irresponsible with there lifestyles? There are documentaries called Food Inc. and King Corn, also Sick, Fat and Nearly Dead is another good one. Read The China Study as well. Atkins is a load of hogwash, the closer we eat to the Earth and the more Raw and Whole foods we consume, trust me, you all would be thankful. I have plenty of research over the many years to back my claims up. More Produce, Juice, more whole grains, pro-biotics, pre-biotics, lentils, rice, veggies rich in colors, try to buy Organic, stay away from GMOs, drink lots of water. Keep away from refined foods, refined wheat products, seek alternative grains, corn, table sugar, table salt, high sodium foods, trans-fats, regular cow milk, processed cheese, anything with added sugar, artificial sweetners, colors, MSG and Fast Food. Study how people eat from Asia, The Middle East and India.

hm why sugar tax? we got free healthcare. those who can afford sugar will keep buying it those who cannot will get food stamps to buy it. and if they get obesse they then can collect disability. and if they need some of the fat removed well the gov will pay for the liposuction. hm, well i guess see the goverment is taking care of their people. feeding them too much and removing the excess. now we just need to turn human fat to sugar! we can feed people their own fat!

The comment preceding this indicates the need for the very important second installment. Eugene McCarthy in creating the federal policy against fat, implicating fat as the cause of obesity and heart disease, and designing the USDA food pyramid which has ruined US health over 3 decades — he created an ill-informed monster.

That may be good for you and this newfound paleo-type crowd but it’s not for the majority. You have no proof that healthy fats are any better than a well-balanced meal with healthy carbs. The fact that you become more health-conscious with a new eating plan causes you to lose excess weight, whether that’s from low-carb, low-fat, high-protein, whatever. The weight loss is what’s making you healthier, your blood work better, not the dam fat intake. Oh, and good luck working out and exercising “properly” running off of fat. Not gonna happen. Low carb, high fat type diets are for couch potatoes or for those who do “moderate to slow” exercise!

1. It is not just a problem of added sugar. Yes, Americans consume too much added sugar; that is not debatable and it certainly is a problem. But the other problem is following the USDA dietary recommendations, which encourage copious consumption of fruits and grains, which the body processes as sugar. Following a USDA diet will still lead to the same problems reported in this article, even if not to the same extent or at the same rate.

2. The problem with sugar is not just that it dulls the brain’s mechanism that tells your body when to stop eating with the result that you end up eating more. That is the old calories in, calories out explanation for why people gain weight. As obvious as that explanation seems, it is wrong. The problem is biochemistry 101: its effect on insulin, which regulates fat metabolism. A diet prominent in grains, legumes, and fruits is linked with the dysregulation of fat metabolism because of insulin dysfunction. Read Gary Taubes’ Good Calories, Bad Calories.

Those “Real Doctors” like Atkins, Weston A. Price, William Davis and Donald W Miller have been telling us this for a number of years. Fear sugar, don’t fear saturated fats… Live a healthy life and go Low-Carb…

This article, like many on nutrition and medicine is about incomplete and non-reputable studies; it is speculative and misleading at best. The very fact that the discussion makes no distinction between the various sugars – Glucose, Fructose, Galactose, Lactose, Sucrose and Maltose for starters – indicates that this piece is neither serious nor credible.

Stories like this one are an example of why Forbes needs to control blog content.

rsborchardt — Yours is the sort of comment that adds precisely nothing to the discussion. What exactly makes the cited studies “incomplete” and “non-reputable”? Can you demonstrate in a “credible” way why your criticism of the studies is worth listening to? Or maybe it’s easier to drop a fly-by comment without substantiation.

As to the distinction between sugars, it’s entirely unnecessary for this piece. By now it’s well known that food manufacturers use fructose and sucrose with abandon, but even knowing that is not necessary for the purposes of this article. What’s important to know is that added sugars in processed foods are contributing to a nationwide health problem. Do you have any grounds to deny this? Can you offer evidence to support a claim that all of the added sugar we’re consuming in these foods is not a problem? What health statistics can you provide to support such a claim?

In summary, your comment is neither serious nor credible. And comments like yours are an example of why Forbes writers should reply to comments, particularly when they are discourteous and shallow.

Mr. DiSalvo, readers do not carry the burden of proof – you do. It is not incumbent on me or anyone else to generate a topical study of whatever you generate.

What is wrong in your article is obvious to anyone who is familiar with academic and scientific publishing. In medical research it is very easy to overstate the certainty of any result because biochemistry is fantastically complex. Science writing for lay readers just about universally ignores the hedged and cautious nature of academic scientific claims. Explanations like “this brain chemical does this and causes that, and it gets worse when…” glibly imply a level of knowledge (and even a level of determinism) that does not exist.

An example is the sacred cow (literally) that fatty foods, red meat in particular, cause heart disease. That has never been on very solid footing, reflected in the shifting causes – cholesterol became good and bad; meat fat became good (Atkins diet); dietary therapy only worked on women, etc.

I appreciate your intentions, especially given what will result from the skyrocketing US rates of diabetes if unchecked (a grossly underreported pending disaster). But there is far too much glib folklore, anti-tech credos and green ideology parading as health related science already. Aside from muddying the waters, that can be very dangerous, and Forbes should not be part of it. A wihle ago there was a Forbes blogger I took to task for asserting that doctors should practice ‘the laying on of hands’ as a curative from ‘alternative’ or ‘holistic’ medicine. He conceded when I pointed out to him that this was precisely the way MRSI was most commonly transmitted.

I would suggest that the nature of your comment does shift the burden of proof, at least to the extent that you should be ready to validate your criticisms. As I am very familiar with academic and scientific publishing, and have been for a number of years including a stint as the managing editor of a peer-reviewed academic journal, I am careful to not assert causal relationships where they don’t exist. That’s why I present multiple studies on any given topic, to offer a number of research perspectives on the problem. I am also careful to use terms that show I am providing conclusions suggested by the studies, and I am open to discussing with anyone the merits or demerits of any given study. What I found offensive about your comment is that you torpedoed all of the research presented–and indeed, the entire discussion–with what I perceived as an arrogant dismissal.

While I would support your criticism of the ‘laying on of hands’ approach, I really can’t see any similarities between that example and what I’m writing about. Whether or not you agree with the conclusions of this research, I’d hope you would agree that it has been conducted with scientifically grounded intentions. The same can’t be said of myth-based misinformation.

To be clear, I am not of the opinion that research “proves” causal relationships in most cases. But, just as in the 60 Minutes segment I linked to, I believe offering research findings around a given topic furthers the discussion and hopefully sparks some new thinking about the problem. In this case, we seem to agree, the problem is quite real.

I think we are talking past each other. I take your points, but they don’t speak to my main point, that nonsense prevails.

If you are familiar with science publishing, you also know that most non-reviewed articles such as those in popular magazines are glib, designed to get readers rather than inform – and usually misinform, at least in the sense of breathlessly reporting the latest medical fad.

That is what irritated me about your article – while it is apparently quite a bit more, it still sounds exactly like trendy junk from a glossy (fen-phen for weight loss and a side of heart damage, anyone?). I read Forbes precisely because its content is generally much more substantial and accurate.

You are certainly aware of the ‘glib’ problem if you are experienced in medical lay publishing. I hope you will at least consider changing your writing style to something more authoritative, for example, mentioning reputable researchers at credible institutions (not necessarily citing publications) and stating the uncertainties. It would also be a real service to take shots at visible pop-science junk so people can distinguish.

Unfortunately, scientific ignorance and innumeracy are so common that any science writer may wll be pursuing a lost cause.

Here in the greated united states of amerikkka sugar is found in everything. salty crackers, wheat, bread, ketchup, mayonaise, vinegar, everything not even meant to be sugary. Partly reason is to sell HFCS (high fructose corn syrup). The trick in the USA is to patent something (research MONSANTO patenting animals, dna, and seedless fruits etc) and capitalizing (see capitalist amerikkka) aka selling it all means every way possible. It’s the american way.